Wilton Food Gel in whatever colors you would like (about a heaping 1/2 tsp of each).

Split batter into two bowls, fill cupcake container 1/4 full with first batter color, then 1/4 full with second batter color. Smooth layers flat with spoon, or bang pan on the counter to help it settle. (Don't overfill!!! Each cupcake should only be about half full--they bake up big.)

Whip butter up until smooth, then add powdered sugar and canned milk alternately until you reach the desired consistency you'd like. (I like to be able to stick my finger in and have the frosting sort of "peak" a bit. Add a capful of vanilla, one quick shake of salt, and food coloring (if desired...I like my frosting white, usually.) Mix altogether for a little bit longer until the frosting looks how you want it.

Let cupcakes cool, frost them, and quickly put on sprinkles or other garnishes. (This frosting recipe tends to harden up quickly, so if you don't do sprinkles immediately, they don't stick well).
Enjoy!!